Lake Vostok (subglacial lake)

Lake Vostok is the largest of Antarctica's 675 known subglacial lakes, which are lakes hidden under the ice. It lies beneath Russia's Vostok Station, under the East Antarctic Ice Sheet, and it is the 16th largest lake in the world by area.

The surface of the lake is about 4,000 metres below the ice surface, and its water may have been sealed off for 15 to 25 million years. Russian scientists drilled through the ice and reached the water on 5 February 2012. Because the lake has been hidden for so long, scientists hope it can show how life might survive on icy worlds far from Earth.

How was it discovered?

Russian geographer Andrey Kapitsa suggested a lake might exist after ice-measuring soundings in 1959 and 1964. Over the next decades Russian and British scientists studied it, and its existence was confirmed in 1993 using a laser altimeter on a satellite, which measured the flat surface of the ice above. The lake was named after Vostok Station, which is named after a ship called Vostok, meaning East in Russian.

Why does it matter?

Because the lake is sealed, it could hold unusual life forms and ancient water, and it resembles the ice-covered oceans thought to exist on Jupiter's moon Europa and Saturn's moon Enceladus. In 2012 drilling reached the lake after an ice core of 3,768 metres, the longest ever. Water gushed up the borehole and mixed with the drilling fluid. Some scientists worried about contaminating the lake and argued for cleaner methods.

On the globe

The model shows the lake hidden under thick ice, with the research station on the surface above.